Patent Document No. 1 teaches a breathing apparatus comprising a filter, a fan unit, a face piece for covering the whole face of a user, a nose cup for covering the mouth and the nose of the user, and a breath monitoring apparatus, wherein the filter is detachably connected to the fan unit, the fan unit is detachably connected to the face piece from the outside of the face piece, the nose cup is detachably connected to the face piece from the inside of the face piece, and the fan unit operates synchronously with the breath timing of the user detected by the breath monitoring apparatus.